Integrated lancet and bodily fluid sensor
A lancing device integrated with a sensing strip and method of making and using the same are provided. A lance and analyte sensing strip are combined in a single, preferably disposable, device. In a preferred embodiment, a slot is provided in a support member so the lance can be engaged by a lance driver and driven into the skin producing a bodily fluid sample from a wound. The sensing area of the sensing strip is adjacent to the wound location reducing dexterity requirements for patients.
This application is a divisional of U.S. patent application Ser. No. 11/704,186, filed Feb. 9, 2007, which is a divisional of U.S. patent application Ser. No. 10/259,798, filed Sep. 30, 2002, which is now U.S. Pat. No. 7,192,405.FIELD OF THE INVENTION
The present invention relates to bodily fluid collection and testing devices. In particular, the present invention relates to a device integrating a lancet and bodily fluid chemistry sensor to provide a single, preferably disposable unit.BACKGROUND OF THE INVENTION
Conventional self-monitoring of blood glucose requires the patient to first load a lancet into a lancer and a separate test strip into a blood glucose meter. The lancer and lancet are then used to prick the finger, and a small drop of blood is squeezed to the surface. Finally, the sample port on the strip is brought into contact with the blood, and the sample is transported to the reaction zone on the strip via capillary action. This can be a labor-intensive, uncomfortable process that requires multiple devices and disposables. Further, patients must repeat this process several times a day in order to manage their disease properly.
Self monitoring of blood glucose is further complicated by the use of small-volume strips when the user is required to manipulate sub-microliter samples (<1 μl). It may be difficult for a person with diabetes to see and align a test strip with such a small sample, particularly for patients who are elderly or who otherwise do not have the dexterity of healthy individuals.
U.S. Pat. No. 5,971,941, to Simons et al., discloses a lancet and test strip integrated into a disposable cartridge. U.S. Pat. No. 6,143,164, to Heller et al., discloses a small volume in-vitro analyte sensor. U.S. Patent Application Publication No. US 2002/0130042 to Moerman et al. appears to discloses an apparatus for detection and quantization of an electrochemically detectable analyte, such as glucose, in blood or interstitial fluid, having a meter, a lancet and an electrochemical sensor. In one embodiment, an absorptive member is disposed to take up a sample of fluid from the pierced skin of the user without movement of the apparatus.SUMMARY OF THE INVENTION
The present invention as exemplified in the embodiments disclosed herein, relates to a device that can be used to obtain a sample of bodily fluid for analyte measurement, having an integrated lancet and detection chemistry (sensor) in a single disposable unit. The unit is preferably sterilizable and compatible with cartridge dispensers. A device according to an embodiment of the invention first allows a droplet of bodily fluid to form on the skin, then ensures automatic alignment of the sample port to the bodily fluid droplet for transfer of the sample to the sample port and sensor surface. An embodiment of the invention uses wicking of the sample to improve sample transport and to remove bodily fluid from wound site.
Another embodiment of the invention is a device for obtaining a sample of bodily fluid by first piercing the skin so that the resulting bodily fluid directly enters a sensor, such as an electrochemical glucose sensor. The device integrates a lancing mechanism and a sensing mechanism, and is preferably adapted to be used with a glucose meter. Thus, a movable lancet or needle is constructed so that it mates with a glucose test strip. The combination device is positioned next to a user's skin so that the wound created by the lancet or needle is designed to be located a precise distance from the operating surface of the sensing strip. The drop of bodily fluid formed by the lancing action impinges on the sensing strip when it reaches a critical size. In one embodiment, the strip employs a capillary tube or a wick to carry the bodily fluid to the sensing surface. The distance from the skin surface to the sensing surface is preferably less than about 2 mm.
The invention will be more readily understood with reference to the embodiments illustrated in the attached drawing figures, in which:
In the drawing figures, it will be understood that like numerals refer to like features and structures.DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the invention will now be described with reference to the attached drawing figures.
Strip 102 is preferably inserted into support member 108 during manufacturing. However, in an alternate embodiment of the invention, support member 108 is manufactured to accept a sensing strip 102, but the sensing strip remains separate until the device 100 is prepared for use. In this embodiment, the strip 102 is preferably kept sterile and inserted into the support member 108 before use. The strip 102 is preferably fixedly attached to support member 108 when installed.
The sensing components 104 preferably employ electrochemical means for sensing an analyte, such as glucose, but other means of sensing analytes which are known in the art are to be considered within the scope of the present invention. In the case of an electrochemical sensor, the chemistry is arranged to make contact with conductive strips (not shown) such that in the presence of bodily fluid a circuit is completed. The term “bodily fluid” used herein will be understood to include blood, interstitial fluid, and combinations thereof. The conductive strips in turn provide electrical contact with the meter portion of the device 112 as shown in
Glucose sensing strips typically employ a capillary flow to transport bodily fluid to the sensing chemistry. In the current device, a capillary flow is also preferably employed, and the strip 102 is initially positioned within the support member 108 such that the capillary flow tube contacts the droplet of bodily fluid generated by the lancet 106. The bodily fluid volume needed is preferably less than 0.5 μl. Adequate volume can be obtained from the fingertip or even off the fingertip, such as on the inner or outer forearm, using relatively pain-free lancets. Bodily fluid flow from a small lancet or needle can be enhanced by a properly designed supporting structure. Typically, an annular structure is brought to bear against the skin with an opening sized to spread the skin with a certain tension such that the wound will be held open after penetration. Bodily fluid is also pushed to the wound by the pressure of holding the device to the skin. In the preferred embodiment of the present invention, the opening and the sensing strip are appropriately positioned relative to each other such that the formation of the bodily fluid drop is optimally positioned for use by the sensing strip.
The strip 102 also preferably contains a wicking device, such as cellulose or nylon fibers, such that bodily fluid emerging from the skin immediately contacts the wick and is transported to the sensing surfaces 104. Such a wick also has the function of removing most bodily fluid from the skin surface, leaving a clean wound site requiring less subsequent activity by the user of the device.
A device according to the embodiment of
The device illustrated in
Using prior art devices, a user typically must first pierce his or her skin with a lancing device, then bring to bear a separate electrochemical sensor contained in a separate or the same housing. With the current device, the lancing and sampling activities are performed using one device and require fewer user actions. Advantageously, there is no requirement for the user to reposition the sensing chemistry over the bodily fluid droplet.
Existing glucose monitors utilize a volume of blood which has previously been brought to the skin surface after application of a separate lance. The lance and sensing strip are typically contained in separate housings, and may also be contained in one housing, but are always separate parts. In the device of
The device of
In a preferred embodiment of the invention, a plurality of the devices shown in
In the presently contemplated best mode of the invention, a plurality of the devices 100 illustrated in
The lance and test strip assemblies 100 are preferably oriented within cartridge 114 such that slot 110 is aligned with a slot 118 in the bottom of cartridge 114 as shown in
A stack of assemblies 200 can be advantageously packaged in a cartridge 114 while in their flat configuration. The bottom-most assembly is partially or fully ejected from the cartridge 114 through opening 116 in order to manipulate the device into the angled orientation shown in
The lancet or needle can be sized according to the amount of bodily fluid desired. Preferably the bodily fluid volume needed is less than 0.5 μl. The penetrating portion of the lancet can be constructed from a flat or round blank. The transport of bodily fluid to the sensing surfaces is accomplished by any of a variety of means, including a capillary flow tube or a wick, or even a vacuum. The device can be used in conjunction with a handheld, portable lancer or meter, or can be made to function in as part of a larger test unit.
Of course the embodiment shown in
The lancer or meter which uses any of the embodiments described herein can also embody design features that make sampling more reliable. An important aspect of bodily fluid sampling is to ensure proper pressure of the lancer housing on the skin. This ensures that the skin surface is positioned correctly relative to the axis of travel of the lancet and the orientation of the strip. This pressure also ensures reliable penetration depth of the lancet, which in turn ensures proper bodily fluid flow. Finally, this pressure also stretches the skin, keeping the wound open to ease bodily fluid flow. A pressure sensor on the lancer housing can be used to indicate to the user that the proper pressure has been achieved, and can also be part of an interlock system preventing premature lancing.
The lance and test strip can be positioned within the portable meter device in such a way that the distance between the piercing site and the sample port of the test strip are precisely spaced. Such a spacing allows adequate bodily fluid volume to build up on the skin before encountering the sample port.
Another advantage of the embodiments described above is that the lance and sensing strip portions of the device can be manufactured independently to a great degree. Thus, sterilization of the lancing tip can be achieved without concern for detrimental effects on glucose sensing chemistry, which can be manufactured with aseptic techniques. The two functioning components of the device are preferably “snap fit” together just prior to packaging to maintain the desired level of sterility.
Proper and precise alignment of the two parts may also be ensured by the lancer or meter. Thus, although each separate part may require precise fabrication, assembly of parts during manufacture does not require precise alignment. For example, in the design shown in
It has been observed that it is much easier to get a bodily fluid sample to flow into a capillary tube if the drop is fully formed. If there is a break in the flow of bodily fluid in a capillary, the capillary action stops. It is also advantageous to create only one wave of bodily fluid flow over the sensing area. Electrochemical sensing relies on a constant delivery rate of glucose to the sensing components (e.g., enzymes). An interrupted flow of bodily fluid can create variable glucose delivery rates to the sensor, causing errors in measurement. Allowing sufficient bodily fluid to form within a drop on the skin before it is carried to the sensing surface (by, for example, a capillary or wick) reduces this source of errors. Moving the sensor strip onto the drop of bodily fluid as illustrated in
Another embodiment of a device 100 according to the present invention is shown in
Driver 504 is connected to driving means (not shown) that are adapted to cock the lance, drive it into the skin of a user, and withdraw the lance so that bodily fluid is free to flow from the small wound created by the lance.
When the device is cocked, lance 106 is first drawn in a proximal direction, causing frangible cap 602 to break away, exposing the lance point, as shown in
It will be appreciated that many embodiments and variations are possible within the scope of the invention.
While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations can be made thereto by those skilled in the art without departing from the scope of the invention as set forth in the claims.
1. A method of manufacturing a bodily fluid sample acquisition and testing device, comprising the steps of:
- inserting a lance into a primary support member having a slot for accessing said lance,
- sterilizing said primary support member and lance; and
- after sterilizing said primary support member and lance, inserting a bodily fluid chemistry sensing strip comprising a sensing area into said primary support member such that said sensing area is adjacent to said lance.
2. The method of claim 1, wherein said sensing area is in electrical contact with two electrodes.
3. The method of claim 1, wherein said sterilization step comprises radiating said primary support member and lance with an electron beam.
4. The method of claim 1, wherein said sterilization step comprises radiating said primary support member and lance with gamma radiation.
Filed: Jan 11, 2011
Publication Date: Jan 19, 2012
Patent Grant number: 8808321
Inventors: John D. DeNuzzio (Chapel Hill, NC), Steven Keith (Chapel Hill, NC), Lawrence A. Monahan (Willow Spring, NC), Phyllis Palmer (Durham, NC), Bill Stewart (Cary, NC), Todd M. Chelak (Waldwick, NJ), Robert E. West (Basking Ridge, NJ), William Allen (Houston, TX), Frederick Karl (Beaverton, OR), Lee Griswold (Norwalk, CT)
Application Number: 12/929,261